Lens actuator

ABSTRACT

There is provided a lens actuator, including: a lens barrel in which at least one lens is provided on an optical axis; a magnetic part provided on one surface of the lens barrel; and a printed circuit board in which a coil pattern part generating electromagnetic force is provided, the printed circuit board having one surface facing the magnetic part, wherein magnetic material is provided on the other surface of the printed circuit board.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/012,896 filed on Aug. 28, 2013 which claims the benefit under 35 USC§ 119(a) of Korean Patent Application No. 10-2012-0112608 filed on Oct.10, 2012, in the Korean Intellectual Property Office, the entiredisclosures of each which are incorporated herein by reference for allpurposes.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a lens actuator, and more particularly,to a lens actuator of which a manufacturing process is simplified andpreventing foreign objects from being introduced thereto during theprocess.

2. Description of the Related Art

In general, it is common nowadays for mobile terminals such as mobilephones, PDAs, portable computers to not only transmit text messages andvoice data but also image data.

Following this trend, recent mobile communications terminals arestandardly equipped with camera modules and are able to transmit imagedata or allow users to make video calls.

In a camera module provided in a mobile communications terminal, a lensmoving device is provided to allow for lens zooming or focusing bymoving a lens in the optical direction.

The lens moving device may be divided into three types, i.e., a rotationmotor type, a piezoelectric actuator (PZT) type, and a voice coil motor(VCM) type, following the manner in which driving force is generated.

The rotation motor type has a relatively complicated structuralmechanism, since it needs to convert rotary motion into linear motion.The PZT type is advantageous in that it is small and light but isdisadvantageous in that it requires a high voltage power source.

The VCM type uses electromagnetic force between a coil through whichcurrent flows and the flux of a magnet to directly move a lens barrelhaving the coil or magnet attached thereto in the optical direction, andhas advantages in that it has a simple structure and is operable at lowvoltage.

However, the existing lens actuator of VCM type requires separationspace between a coil and a position sensor, and requires a separateprocess to electrically connect the coil and the position sensor to aprinted circuit board, such that the process is complicated, andreliability is lowered if the assembly tolerance is large.

Further, foreign objects may be generated during soldering tocontaminate the inside of the lens actuator, thereby lowering thereliability.

Patent Document 1 discloses a camera module having a structure in whichan electromagnetic part and a hole sensor are mounted in a yoke.

RELATED ART DOCUMENT

(Patent Document 1) Korean Patent Laid-Open Publication No. 2011-0064147

SUMMARY OF THE INVENTION

An aspect of the present invention provides a lens actuator having asimplified manufacturing process, reduced manufacturing costs, andpreventing foreign objects from being introduced thereto during themanufacturing process by connecting a coil and circuit components to aprinted circuit board without using wire bonding.

An aspect of the present invention also provides a lens actuator havinga simplified manufacturing process due to a reduction in a number ofcomponents used therein by applying magnetic material to a printedcircuit board without requiring a separate yoke member.

An aspect of the present invention also provides a lens actuator capableof being reduced in size by reducing separation space between a coil,circuit components and a yoke.

According to an aspect of the present invention, there is provided alens actuator, including: a lens barrel in which at least one lens isprovided on an optical axis; a magnetic part provided on one surface ofthe lens barrel; and a printed circuit board in which a coil patternpart generating electromagnetic force is provided, the printed circuitboard having one surface facing the magnetic part, wherein magneticmaterial is provided on the other surface of the printed circuit board.

The coil pattern part may be a metal layer patterned on the printedcircuit board.

The coil pattern part may be a winding coil embedded in the printedcircuit board.

The printed circuit board may have an integrated circuit componentmounted therein.

The printed circuit board may have a position sensor mounted therein tosense the position of the lens barrel.

The coil pattern part may surround the position sensor.

The magnetic material may be magnetic paste.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is an exploded perspective view of a lens actuator according toan embodiment of the present invention;

FIG. 2 is a perspective view of the front of a printed circuit boardaccording to an embodiment of the present invention;

FIG. 3 is a perspective view of the rear of a printed circuit boardaccording to an embodiment of the present invention; and

FIG. 4 is a cross-sectional view taken along line A-A′ of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. The invention may,however, be embodied in many different forms and should not be construedas being limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art. In the drawings, the shapes and dimensions ofelements may be exaggerated for clarity, and the same reference numeralswill be used throughout to designate the same or like elements.

Firstly, the term “optical axis direction” is defined as a verticaldirection with respect to “◯” shown in FIG. 1.

FIG. 1 is an exploded perspective view of a lens actuator according toan embodiment of the present invention.

Referring to FIG. 1, the lens actuator according to the embodiment ofthe present invention may include a lens barrel 100, a magnetic part200, a printed circuit board 300, a housing 400 and a cover 500.

The lens barrel 100 is a hollow cylinder in which at least one lens maybe provided on the optical axis.

The lens barrel 100 is coupled to the housing 400 so that it is movableon the optical axis, and the magnetic part 200 may be provided on a partof the surface of the lens barrel 100 as a driving unit for moving thelens barrel 100 in the optical direction.

By providing the magnetic part 200 on the part of the surface of thelens barrel 100, the lens barrel 100 can be moved in the opticaldirection by the interaction between a coil pattern part 310 provided onthe printed circuit board 300 and the magnetic part 200.

That is, the magnetic part 200 generates a constant magnetic field, andelectromagnetic interaction occurs between the magnetic part 200 and thecoil pattern part 310 when the coil pattern part 310 is powered, suchthat the lens barrel 100 can be moved in the optical axis direction byLorentz force generated in the vertical direction due to current andmagnetic field.

Here, the shape of the magnetic part 200 is not specifically limited, aslong as it is possible to move the lens barrel 100 in the optical axisdirection by the electrical interaction with the coil pattern part 310.

The external power may be provided by the printed circuit board 300,specifically by the power connection terminal 340 of the printed circuitboard 300.

The housing 400 is to support the lens barrel 100, in which the lensbarrel 100 is accommodated.

Accordingly, the housing 400 may have internal space to accommodate thelens barrel 100, and the shapes of the housing 400 and the internalspace are not specifically limited.

The cover 500 may have a shape to cover the lens barrel 100 moving inthe optical axis direction and the housing 400, and may be coupled tothe housing 400.

The printed circuit board 300 may have the coil pattern part 310 and aposition sensor 320 provided therein.

The detailed configuration of the printed circuit board 300 will bedescribed in detail with reference to FIGS. 2 to 4.

The printed circuit board 300 may be coupled to the housing 400 so thatits one surface faces the magnetic part 200.

Accordingly, the coil pattern part 310 provided on the printed circuitboard 300 and the magnetic part 200 provided on the one surface of thelens barrel 100 may face and interact with each other to generate theLorentz force.

After the lens barrel 100 and the printed circuit board 300 are coupledto the housing 400, the cover 500 is coupled therewith to protect thelens actuator from external impacts.

FIG. 2 is a perspective view of the front of a printed circuit boardprovided in a lens actuator, according to an embodiment of the presentinvention; FIG. 3 is a perspective view of the rear of a printed circuitboard provided in a lens actuator, according to an embodiment of thepresent invention; and FIG. 4 is a cross-sectional view taken along lineA-A′ of FIG. 2.

Referring to FIGS. 2 to 4, the printed circuit board 300 provided in alens actuator according to an embodiment may have a coil pattern part310 and a position sensor 320 therein.

The coil pattern part 310 may be a winding coil pattern embedded in theprinted circuit board 300 or may be a metal layer patterned in theprinted circuit board 300.

Here, the coil pattern part 310 is formed in and electrically connectedto the printed circuit board 300 internally, such that no separate wirebonding is required, thereby simplifying the manufacturing process.

Additionally, in case of wire bonding, foreign objects generated duringthe process may contaminate the inside of a lens actuator so thatreliability may be lowered. However, in the case that the coil patternpart 310 and the printed circuit board 300 are electrically connectedwithin the printed circuit board 300 as described above, the aboveproblem can be avoided.

The coil pattern part 310 electrically connected to the printed circuitboard 300 may generate electromagnetic force to move the lens barrel 100upon receiving current from the printed circuit board 300.

In addition, the coil pattern part 310 may have an outer surfaceconforming to an outer surface of the magnetic part 200 provided on onesurface of the lens barrel 100.

In the lens actuators according to the related art, instead of forming acoil pattern inside a printed circuit board, a coil separated from aprinted circuit board is mounted on the upper surface of a printedcircuit board, such that the winding shape of the coil cannot be freelychosen. In the coil pattern part 310 according to the embodiment of thepresent invention, however, the shape of the coil may be determinedaccording to the shape of the magnetic part 200, thereby improvingmagnetic and spatial efficiency.

The location sensor 320 may be mounted in the printed circuit board 300.

Here, the position sensor 320 is mounted in and electrically connectedto the printed circuit board 300 internally, such that no separate wirebonding is required. Accordingly, like the coil pattern part 310, themanufacturing process can be simplified and the reliability can beimproved.

Further, by mounting the position sensor 320 in the printed circuitboard 300, no separation space between the position sensor 320 in thehousing 400 is required, such that the lens actuator can be reduced insize and manufacturing tolerance during the manufacturing process can bereduced.

The position sensor 320 senses a current position of the lens barrel 100to provide it to a control unit (not shown), and the control unit (notshown) uses the information on the current position of the lens barrel100 received from the position sensor 320 and information on a targetposition to which the lens barrel 100 is moved so as to apply anappropriate current to the coil pattern part 310, thereby controllingthe movement of the lens barrel 100.

Although the position sensor 320 is mounted in the printed circuit board300 in this embodiment, the present invention is not limited to theposition sensor 320 but other circuit components may be mounted in theprinted circuit board.

That is, as a driving chip for driving the lens actuator according tothe embodiment of the present invention, an integrated circuit (IC)component may be mounted in the printed circuit board 300.

Since the integrated circuit (IC) component as well as the positionsensor 320 may be mounted in the printed circuit board 300, themanufacturing process can be simplified.

One surface of the printed circuit board 300 may face the magnetic part200, and magnetic material 330 may be provided on its other surface.

Specifically, the magnetic material 330 may be applied to the othersurface of the printed circuit board 300, and may be magnetic paste. Byapplying the magnetic material 330 to the other surface of the printedcircuit board 300, magnetic flux may smoothly flow to the magnetic part200 through the coil pattern part 310.

Conventionally, a separate yoke member is prepared and is attached to acoil. However, according to the embodiment of the present invention inwhich the magnetic material 330 is applied to the other surface of theprinted circuit board 300, components are reduced in number, therebysimplifying the process.

As in the above-described embodiment, by including the coil pattern part310, the position sensor 320, the integrated circuit (IC) component andthe magnetic material 330 in the printed circuit board 300, themanufacturing process can be simplified, manufacturing costs can bereduced and foreign objects generated by soldering and the like can beprevented.

In addition, since no separation space between the coil, the integratedcircuit (IC) component and the yoke member is required, the lensactuator can be reduced in size.

As set forth above, according to embodiments of the present invention,the manufacturing process can be simplified, manufacturing costs can bereduced, and foreign objects can be prevented from being introducedduring the process by way of connecting a coil and circuit components toa printed circuit board without using wire bonding.

Further, the manufacturing process can be simplified due to a reductionin a number of components by way of applying a magnetic material to aprinted circuit board without requiring a separate yoke member.

Moreover, the lens actuator can be reduced in size by way of reducingseparation space between a coil, circuit components and a magneticmaterial.

While the present invention has been shown and described in connectionwith the embodiments, it will be apparent to those skilled in the artthat modifications and variations can be made without departing from thespirit and scope of the invention as defined by the appended claims.

What is claimed is:
 1. A lens actuator, comprising: a lens barrel in which at least one lens is provided on an optical axis; a magnetic part provided on one surface of the lens barrel; and a printed circuit board in which a coil pattern part generating electromagnetic force is provided, the printed circuit board having one surface facing the magnetic part, wherein magnetic material is provided on the other surface of the printed circuit board.
 2. The lens actuator of claim 1, wherein the coil pattern part is a metal layer patterned on the printed circuit board.
 3. The lens actuator of claim 1, wherein the coil pattern part is a winding coil embedded in the printed circuit board.
 4. The lens actuator of claim 1, wherein the printed circuit board has an integrated circuit component mounted therein.
 5. The lens actuator of claim 1, wherein the printed circuit board has a position sensor mounted therein to sense the position of the lens barrel.
 6. The lens actuator of claim 5, wherein the coil pattern part surrounds the position sensor.
 7. The lens actuator of claim 1, wherein the magnetic material is magnetic paste. 